What is Sustainable Structural Engineering, and why is It More Important Now than Ever?

With intensifying sustainability outlook that clients and construction regulations set, the bar is ever-rising for structural engineers in the construction industry. A high level of attention put on every industry’s environmental consequences has kept increasing the number of structures that embody showable sustainable practices that meet clients’ expectations.

In this article, we’ll discuss sustainable structural engineering and state its relevance to the modern world. We’ll answer the question, what is the difference between structural and sustainable structural engineering? We’ll share the current sustainable structural engineering solution and provide insight into how structural engineers can adopt more sustainable designs.

What is Sustainable Structural Engineering, and why is It More Important Now than Ever?

Sustainable structural engineering is a practice that requires structural engineers, just like any other profession in any other industry, to minimize environmental pollution. Sustainable structural engineering practices include:

  • Minimizing the incorporated energy in construction materials
  • Minimizing on-site waste
  • Minimizing energy use of the finished construction product
  • Utilizing recyclable and renewable structural materials
  • Maximize the durability of the structural system
  • Conserving the environment serves as the natural habitat before, during, and after the structural construction phase.

Why are sustainable structural engineering practices more critical now than ever? The world is currently facing climatic challenges such as:

  • Global warming threatening the existence of coral reefs and sea ice
  • Constant rising sea levels increasingly create the risk of catastrophic flooding
  • Changing (unpredictable) weather patterns that threaten food production

The built environment plays a significant role in controlling climatic challenges since it influences the environment through energy consumption and emissions. Structural engineering activities involve:

  • Construction activities in sites hosting green fields that risk destroying wildlife habitats
  • Consumption of energy during construction
  • The heavy plant machinery which relies on carbon fuels
  • Incorporated energy within construction materials
  • Buildings’ energy requirement during the usage phase

Today, construction projects account for 40% of carbon emissions and 36% of the energy used globally. The areas that structural engineers must pay keen interest in include:

  • Quarrying for raw materials that risks polluting water sources (underground and surface waters)
  • Manufacturing and transportation of construction materials, which influence carbon emissions. For instance, cement manufacturing contributes 2.8 billion tons of carbon emissions to the environment. The current increase in construction activities and urbanization risk raising it to 4 billion tons annually.

Having informed decisions at each stage of a new construction project bring huge environmental influence, and applying sustainable construction approaches will minimize your company’s negative influence on the environment. An example is the sustainable waste management approaches during the structure’s usage. Additionally, green structures require less operating costs. Research claims that applying the latest sustainable structural construction technologies could deliver annual savings worth $400 billion in global spending on energy. As a client, you must know that your specification for a new building or building modification significantly affects the project’s specification and, consequently, the structure’s operation costs.  

Role of Structural Engineers in Achieving Structural Sustainability

Structural engineers plan, analyze, design, construct, inspect, monitor, maintain, rehabilitate and demolish temporary and permanent structures or structural elements. Structural engineers design robust, durable, and stable structural elements. Structural engineering practices and sustainability practices have the same goals.

To achieve structural sustainability in buildings and structural components, sustainable structural engineering practices direct structural engineers to:

  • Consider technical, environmental, social, economic, and aesthetic aspects of the structures during the design, construction, use, and maintenance stages.
  • Know the design function of the structure, such as municipal, educational, residential, coastal, historical, religious, commercial, institutional, multi-family, or mixed-use.
  • Design with the mindset that the depletion rate of raw or natural materials is high
  • Design for a sustainable structural material that consumes reduced energy, emits minimized carbon gases and is durable and robust to perform the intended function. Structural materials include concrete, wood, steel, aluminum, plastics, and composites.
  • Minimize the use of steel and concrete and maximize the use of materials with less environmental degradation.
  • Design for sustainable structural elements such as beams, trusses, columns, arches, plates, shells, and catenaries. It involves practicing structural analysis of these structural elements to ensure that they are sustainable for the structure. For example, analyzing the statically determinate and indeterminate structural beams under loadings.
  • Design for maximum structural flexibility to enable future changes in the structural use of the building in its lifetime.

Current Sustainable Structural Engineering Solutions

Structural engineers can take several steps to control the environmental effects of the structural design and improve its value. The current sustainable structural engineering solution, including

  • Improvement in life-cycle performance
  • Specification of recycled materials
  • Use of substitute materials.

Improvement in Structural Life-Cycle Performance

Structural engineers design most structures to reduce the initial project’s cost instead of the entire project’s life costs. For instance, the cost of constructing a bridge is usually lower than the costs of maintaining and demolishing it, yet engineers hardly consider the entire structural life design costs.

You can slightly increase the initial construction costs to reduce maintenance dramatically and allow for salvage or disposal at the ultimate structural life; as a result, you will reduce the structural life-cycle costs. When you reduce the life cycle costs, structures become more sustainable than other structural engineering practices. Sustainable structural engineering has focused on improving structural life-cycle performance and made it an objective to improve structures’ economic and environmental performance significantly.

For example, structural engineers who designed Traversina Bridge in Switzerland used locally available timber to maintain the bridge without additional support. The design makes the bridge sustainable since the design objective has helped establish a structure with improved environmental performance and economic life cycle costs.

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Figure 1: Traversing Bridge showing the use of locally available timber to enhance its sustainability.

Specification of Recycled or Salvaged Structural Materials

The traditional construction method excavates raw resources and processes them into useful construction products. Structural engineers now look for alternative material sources. The built environment is estimated to contain more copper than their ore. Hence call you to consider mining the construction materials in the built environment.

Today’s sustainable structural engineering recycles and salvages construction materials that former engineers sometimes extracted back from the earth. Salvaging and recycling solve growing waste disposal and landfill challenges.

The current sustainable structural engineers design and make concrete from waste products and salvaged materials. When making concrete for sustainable structural elements, you can use fly ash, waste products, and recycled aggregates to replace Portland cement and natural aggregates. We hope that future structural engineers will make concrete primarily from waste products and salvaged materials since the resultant product has low initial costs and improved environmental and engineering performance.

Moreover, structural designers have also sought to maximize structural design flexibility to give room for future changes in the structural use of the building during its service life. An example is Stansted Airport Terminal, which provides maximum flexibility and uses recycled materials. Stansted Airport Structure uses steel, the best structural material for sustainable construction. Steel modules provide a long span that enables significant interior flexibility and building expansion for future needs. Lastly, if the user does not need the structure, the structural engineer disassembles the structural elements and reuses them to build another structure. Salvaging structural materials like steel is better than recycling because of the high energy needed for recycling.

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Figure 2: Stansted Airport displays the use of steel modules to provide long-span and other design features that enhance its sustainability.

Use of Substitute Materials

Structural engineers in the United States use two basic structural materials: concrete and steel. Regrettably, concrete and steel use massive amounts of energy to process and emit much carbon into the environment. These structural materials have inherent benefits and will remain dominant structural systems. However, you can explore substitute structural materials. Sustainable structural engineering involves investigating construction materials with low environmental effects. Structural engineers work to build and implement structural elements made of paper. You can explore substitute materials specifically for structures with short life plans to attain engineering goals of economics and efficiency while minimizing construction environmental effects.

How Structural Engineers Can Adopt More Sustainable Designs

How can structural engineers adopt more sustainable designs? Structural engineers can go deep to adopt more sustainable designs by minding:        

  • Sustaining living
  • Zero waste
  • Zero carbon

Structural engineers can mind sustainable living when designing residential structures for their clients. It involves putting effort into building structures without volatile organic materials (VOC) and sufficient water supply to promote:

  • Motivation
  • Good lifestyles,
  • Workers’ well-being and health.

Sustainable structural engineering practices that create a framework to consider consumers’ health and happiness enable structural engineers to adopt more sustainable designs.

Structural engineers focus on waste reduction before, during, and after construction. However, you can think about ways to design for reuse or deconstruction. Deconstruction is the ability to retrieve a structure’s elements for ready reuse. Structural engineers can use bolted joint connections instead of welded ones. Thus, you can maximize the chances to design for deconstruction to promote zero waste at the end of the structure’s life. A design to deconstruct the structural system considers material durability, the usability of reversible connections, prefabrication of structural elements, and the use of the material of minimized lifetime incorporated energy. Zero waste structural design is one-way structural engineers can adopt more sustainable designs.

Thirdly, structural engineers can focus on zero carbon emissions to adopt more sustainable designs. You can pay attention to locally available resources for construction materials, primarily recycled or reclaimed structural materials. When considering on-site materials for construction design, you can reduce carbon emissions from long-distance transportation. In addition, you also support the local economy. Examples of such locally available materials include using grated sand to make sand for constructing outdoor structural elements like pavements. Similarly, the application of reused steel qualifies to be a locally available material that promotes zero emission. Hence, you can consider achieving zero emissions to adopt more sustainable designs.

Long-Term Challenges in the Face of Structural Engineering

Even though sustainable engineering provides solutions to minimize environmental pollution in the built environment, several long-term challenges face structural engineers. The challenges strike the profession in 3 main areas:

  • Practice
  • Research
  • Education

The Practice

Structural engineering practice encounters crucial problems in the attempt to provide construction sustainability, such as emerging policies and the economic nature of sustainable engineering practices. The construction industry rewards structural engineers based on the initial construction costs instead of the project’s life cycle costs. Sustainable structural engineering results in low life cycle costs after high initial costs. This makes structural engineers design and construct bridges and buildings with high life cycle costs and more environmental consequences. For instance, the low life cycle costs can drastically reduce spending (government and private sector) spending on structures. Therefore, effective policies allow structural engineers to account for disposal and maintenance costs and initial costs (entire life design) during structural design.

The Research

Structural engineering is constantly focusing on evaluating and maintaining available structures. The increase in the invention of non-destructive structural testing approaches over the past few years proves the claim. It shows that structural engineers are busy improving built environment sustainability by extending the lifetime of available structures instead of building new structures. Therefore, structural engineers require new options for practicing sustainable construction. In addition, the structural engineering community needs new materials made from waste products to construct structures with lower economic costs and environmental impact. Ideally, a sustainable built environment would assist in absorbing excess carbon gases and using waste products from all other sectors to solve the landfill challenges. The objective of a sustainable built environment needs collaboration between practice, government, and learning institutions. Therefore, research in sustainable structural engineering must attach to design, policy, social and economic impacts.

The Education

Only 6% of high school graduates want to study structural engineering in college. The figure has reduced from 9% back in 1992. This is challenging since structural engineering education is the best way to create engineers and leaders.

Conclusion

Structural engineering practices consume a large share of natural resources. However, with the developing issues about climate change and the depletion of naturally existing construction materials, there is a growing pressure on structural engineers to reduce the environmental impacts of their construction practices by practicing sustainable structural construction or green building.

Revised construction policies can change the minimum required levels for designing and constructing a structure today. A structural engineer needs to know the meaning of sustainability, its importance in improving the well-being of the built and natural environment, and the steps that the construction industry takes to improve the environmental impact of construction activities on society. Therefore, you must advance your construction technology to provide structures with reduced energy needs and embodied energy.

References

·           https://courses.washington.edu/cee380/ochsendorf.pdf

·           https://www.istructe.org/resources/blog/5-actions-design-sustainably/

·          https://www.structuremag.org/?p=17858

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